package sqlSession;

import config.BoundSql;
import pojo.Configuration;
import pojo.MappedStatement;
import utils.GenericTokenParser;
import utils.ParameterMapping;
import utils.ParameterMappingTokenHandler;

import javax.sql.DataSource;
import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;


public class SimpleExecutor implements  Executor{


    @Override
    public <E> Integer update(Configuration configuration, MappedStatement mappedStatement, Object[] params) throws Exception {
        PreparedStatement preparedStatement = getPreparedStatement(configuration, mappedStatement, params);
        return preparedStatement.executeUpdate();
    }

    @Override
    public List<Object> query(Configuration configuration, MappedStatement mappedStatement, Object[] params) throws Exception {
        PreparedStatement preparedStatement = getPreparedStatement(configuration, mappedStatement, params);
        ResultSet resultSet = preparedStatement.executeQuery();
        String resultType = mappedStatement.getResultType();
        Class<?> resultTypeClass = getClassType(resultType);
        ArrayList<Object> objects = new ArrayList<>();
        while (resultSet.next()) {
            //无参构造一实例
            Object o = resultTypeClass.getDeclaredConstructor().newInstance();
            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i = 1; i <= metaData.getColumnCount(); i++) {
                // 字段名
                String columnName = metaData.getColumnName(i);
                // 字段的值
                Object value = resultSet.getObject(columnName);
                //使用反射或者内省，根据数据库表和实体的对应关系，完成封装
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o,value);
            }
            objects.add(o);
        }
        return objects;
    }

    private Class<?> getClassType(String paramterType) throws ClassNotFoundException {
        if(paramterType!=null){
            Class<?> aClass = Class.forName(paramterType);
            return aClass;
        }
        return null;
    }

    private BoundSql getBoundSql(String sql) {
        //标记处理类：配置标记解析器来完成对占位符的解析处理工作
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{", "}", parameterMappingTokenHandler);

        String parseSql = genericTokenParser.parse(sql);
        //#{}里面解析出来的参数名称
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();
        BoundSql boundSql = new BoundSql(parseSql,parameterMappings);
        return boundSql;
    }


    private PreparedStatement getPreparedStatement(Configuration configuration, MappedStatement mappedStatement, Object[] params) throws Exception {
        DataSource dataSource = configuration.getDataSource();
        Connection connection = dataSource.getConnection();
        String sql = mappedStatement.getSql();
        BoundSql boundSql = getBoundSql(sql);
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());
        //参数类的路径
        String paramterType = mappedStatement.getParamterType();
        Class<?> paramtertypeClass = getClassType(paramterType);
        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for(int i=0;i<parameterMappingList.size();i++){
            //参数名
            String content = parameterMappingList.get(i).getContent();
            Field declaredField = paramtertypeClass.getDeclaredField(content);
            declaredField.setAccessible(true);
            //搜索条件对应属性的值
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i+1,o);
        }

        return preparedStatement;
    }


}
